电液混合全冗余并联机构驱动优化

基于冗余并联机构主动输入约束螺旋线性相关性的分析,以Stewart平台机构为原型,构造12-UPS全冗余驱动并联机构。通过比较电动驱动和液压驱动的不同,确定机构适宜采用电动液压混合驱动形式。应用影响系数法建立该机构的动力学模型。为区分处理电动缸和液压缸,以零内力为约束条件对驱动力进行优化。分别以驱动力平方和最小和驱动功率平方和最小为目标,应用库恩—图克定理研究机构的驱动力优化过程。数值算例表明,零内力条件下以驱动功率平方和最小为目标的优化方法最佳。该优化方式能够充分发挥电动、液压驱动各自的优点而避免其缺点,适用于电液混合驱动的全冗余并联机构。

Drive Optimization of Parallel Mechanism with Electro-hydraulic Drive and Fully Redundancy

The 12-UPS parallel mechanism with fully redundant actuation was constructed on the basis of the Stewart platform and the analysis of linear correlation of constraint screws of active inputs in redundant actuation parallel mechanism. By comparing the differences of electric drive and hydraulic drive, the electro-hydraulic drive mode was determinded to be used suitably. The influence coefficient method was applied to establish the dynamic models of the mechanism. In order to distinguish electric cylinder and hydraulic cylinder in processing, zero internal forces were considered as constraint conditions when optimizing the driving forces. The Kuhn-Tuck-er theorem was applied to study the driving forces' optimization procedure of mechanism, withing the minizied quadratic sum of driving forces and the minizied quadratic sum of the driving power respectively. The numerical example shows that the optimization method u-sing minimizing the quadratic sum of drive powers is the best under the condition of zero internal forces. This optimization method can not only fully exert the merits of electric and hydraulic drive but also avoid its disadvantages, so it is applicable to the parallel mecha-nism with electro-hydraulic drive and fully redundant actuation.